Ocular implants with asymmetric flexibility

ABSTRACT

An ocular implant having an inlet portion and a Schlemm&#39;s canal portion distal to the inlet portion, the inlet portion being disposed at a proximal end of the implant and sized and configured to be placed within an anterior chamber of a human eye, the Schlemm&#39;s canal portion being arranged and configured to be disposed within Schlemm&#39;s canal of the eye when the inlet portion is disposed in the anterior chamber.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/246,363, filed Apr. 7, 2014, now U.S. Pat. No. 9,039,650; which is acontinuation of U.S. application Ser. No. 12/236,225, filed Sep. 23,2008, now U.S. Pat. No. 8,734,377, which is a continuation-in-part ofU.S. application Ser. No. 11/860,318, filed Sep. 24, 2007, now U.S. Pat.No. 7,740,604, the disclosures of which are incorporated by reference asif fully set forth herein.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to devices that are implantedwithin the eye. More particularly, the present invention relates todevices that facilitate the transfer of fluid from within one area ofthe eye to another area of the eye.

BACKGROUND OF THE INVENTION

According to a draft report by The National Eye Institute (NEI) at TheUnited States National Institutes of Health (NIH), glaucoma is now theleading cause of irreversible blindness worldwide and the second leadingcause of blindness, behind cataract, in the world. Thus, the NEI draftreport concludes, “it is critical that significant emphasis andresources continue to be devoted to determining the pathophysiology andmanagement of this disease.” Glaucoma researchers have found a strongcorrelation between high intraocular pressure and glaucoma. For thisreason, eye care professionals routinely screen patients for glaucoma bymeasuring intraocular pressure using a device known as a tonometer. Manymodern tonometers make this measurement by blowing a sudden puff of airagainst the outer surface of the eye.

The eye can be conceptualized as a ball filled with fluid. There are twotypes of fluid inside the eye. The cavity behind the lens is filled witha viscous fluid known as vitreous humor. The cavities in front of thelens are filled with a fluid know as aqueous humor. Whenever a personviews an object, he or she is viewing that object through both thevitreous humor and the aqueous humor.

Whenever a person views an object, he or she is also viewing that objectthrough the cornea and the lens of the eye. In order to be transparent,the cornea and the lens can include no blood vessels. Accordingly, noblood flows through the cornea and the lens to provide nutrition tothese tissues and to remove wastes from these tissues. Instead, thesefunctions are performed by the aqueous humor. A continuous flow ofaqueous humor through the eye provides nutrition to portions of the eye(e.g., the cornea and the lens) that have no blood vessels. This flow ofaqueous humor also removes waste from these tissues.

Aqueous humor is produced by an organ known as the ciliary body. Theciliary body includes epithelial cells that continuously secrete aqueoushumor. In a healthy eye, a stream of aqueous humor flows out of theanterior chamber of the eye through the trabecular meshwork and intoSchlemm's canal as new aqueous humor is secreted by the epithelial cellsof the ciliary body. This excess aqueous humor enters the venous bloodstream from Schlemm's canal and is carried along with the venous bloodleaving the eye.

When the natural drainage mechanisms of the eye stop functioningproperly, the pressure inside the eye begins to rise. Researchers havetheorized prolonged exposure to high intraocular pressure causes damageto the optic nerve that transmits sensory information from the eye tothe brain. This damage to the optic nerve results in loss of peripheralvision. As glaucoma progresses, more and more of the visual field islost until the patient is completely blind.

In addition to drug treatments, a variety of surgical treatments forglaucoma have been performed. For example, shunts were implanted todirect aqueous humor from the anterior chamber to the extraocular vein(Lee and Scheppens, “Aqueous-venous shunt and intraocular pressure,”Investigative Ophthalmology (February 1966)). Other early glaucomatreatment implants led from the anterior chamber to a sub-conjunctivalbleb (e.g., U.S. Pat. No. 4,968,296 and U.S. Pat. No. 5,180,362). Stillothers were shunts leading from the anterior chamber to a point justinside Schlemm's canal (Spiegel et al., “Schlemm's canal implant: a newmethod to lower intraocular pressure in patients with POAG?” OphthalmicSurgery and Lasers (June 1999); U.S. Pat. No. 6,450,984; U.S. Pat. No.6,450,984). In addition to drug treatments, a variety of surgicaltreatments for glaucoma have been performed. For example, shunts wereimplanted to direct aqueous humor from the anterior chamber to theextraocular vein (Lee and Scheppens, “Aqueous-venous shunt andintraocular pressure,” Investigative Ophthalmology (February 1966)).Other early glaucoma treatment implants led from the anterior chamber toa sub-conjunctival bleb (e.g., U.S. Pat. No. 4,968,296 and U.S. Pat. No.5,180,362). Still others were shunts leading from the anterior chamberto a point just inside Schlemm's canal (Spiegel et al., “Schlemm's canalimplant: a new method to lower intraocular pressure in patients withPOAG?” Ophthalmic Surgery and Lasers (June 1999); U.S. Pat. No.6,450,984; U.S. Pat. No. 6,450,984).

SUMMARY OF THE INVENTION

While some prior glaucoma treatment implants did provide a flow pathbetween the anterior chamber and Schlemm's canal, these prior devicesfailed to recognize (1) the importance of supporting a significantportion of Schlemm's canal in a patent state or (2) the harm to adjacenttissue caused by relatively high fluid flow rates at or around anyportion of the device. The ocular implant devices and methods of thisinvention address one or both of these design criteria.

According to one aspect of the invention, the ocular implant may beinserted into Schlemm's canal of an eye to facilitate the flow ofaqueous humor out of the anterior chamber of the eye by, e.g.,supporting tissue in the trabecular meshwork and in Schlemm's canal. Theflow facilitated by the presence of the ocular implant may include axialflow along Schlemm's canal, flow into Schlemm's canal from the anteriorchamber of the eye, and flow leaving Schlemm's canal via the outletsthat communicate with the canal.

After exiting Schlemm's canal via the outlets, aqueous humor enters thevenous blood stream and is carried along with the venous blood leavingthe eye. The pressure of the venous system tends to be around 5-10 mm Hgabove atmospheric pressure. Accordingly, the venous system provides apressure backstop which assures that the pressure in the anteriorchamber of the eye remains above atmospheric pressure.

Some exemplary ocular implants according to this invention have a bodywith a plurality of open areas, strut areas and spine areas formedtherein. The strut areas and spine areas act as reinforcing structuresthat hold the walls of Schlemm's canal in a patent state so that thewalls of the canal provide a flow channel or fistula. Furthermore, thespine areas and the strut areas may be sized and shaped to reinforceSchlemm's canal while occupying a relatively small portion of the totallateral cross sectional area of Schlemm's canal. When this is the case,the ocular implant provides minimal obstruction to aqueous humor flowingalong the length of Schlemm's canal. Reinforcing Schlemm's canal withminimal metal mass present in the canal may also encourage a safehealing response over time.

Some exemplary ocular implants according to this invention have a bodydefining openings that are sized and shaped to facilitate the lateralflow of aqueous humor across and/or through the body of the ocularimplant. The lateral flow of aqueous humor may include the flow ofaqueous humor through the trabecular mesh and into Schlemm's canal. Thelateral flow of aqueous humor may also include the flow of aqueous humorthrough outlets that communicate with Schlemm's canal.

One aspect of the invention provides an ocular implant having a bodyextending along a generally curved longitudinal axis, the curvedlongitudinal axis defining a first plane, the body having a diameter ofbetween 0.005 inches and 0.04 inches and being adapted to be disposedwithin a canal of Schlemm in a human subject's eye; wherein the body hasa first flexibility when bent along the first plane and a secondflexibility different from the first flexibility when bent along asecond plane that intersects the first plane and is not coincident withthe first plane, such as, e.g., a plane orthogonal to the first plane.In some embodiments, the body has a shape that is symmetric about thefirst plane.

The implant of the invention may have a variety of features. In someembodiments, the implant body has circumferential material coverage incross-sections perpendicular to the longitudinal axis that is less than360 degrees over an entire length of the body. The body may define anelongate slot that opens radially outward when the body is unrestrained.

In some embodiments, the body has a plurality of pairs of tissuesupporting frames and a spine attached to each adjacent pair of tissuesupporting frames. Each spine may have a shape that is symmetric aboutthe first plane, and each tissue supporting frame may have a shape thatis symmetric about the first plane. In some embodiments, the spines arelongitudinally aligned with one another.

In some embodiments, each spine has a first minor side, a first majorside, a second minor side, and a second major side; with each spinehaving a thickness extending between at least one point on each majorside and at least one point on the second major side; each spine havinga width extending between at least one point on each minor side and atleast one point on the second minor side; and an aspect ratio of thewidth to the thickness being greater than about 2. In some embodiments,the first major side and the second major side are opposite one another.Also, the first major side may have a concave surface, and the secondmajor side may have a convex surface. The concave surface and the convexsurface may be concentric.

In some embodiments, each tissue supporting frame has at least a firststrut and a second strut. Each strut may follow, e.g., acircumferentially undulating path while extending longitudinally betweena first spine and a second spine.

In some embodiments, each strut has a first minor side, a first majorside, a second minor side, and a second major side. In such embodiments,each strut has a thickness extending between at least one point on thefirst major side and at least one point on the second major side; awidth extending between at least one point on the first minor side andat least one point on the second minor side; and an aspect ratio of thewidth to the thickness being greater than about 2. In some embodiments,the first major side and the second major side are opposite one another.Also, the first major side may have a concave surface, and the secondmajor side may have a convex surface. The concave surface and the convexsurface may be concentric.

In some embodiments, the body of the ocular implant exhibitssuperelastic properties. The body may be made of nickel and titanium inappropriate proportions, such as, e.g., wherein the weight percent ofnickel is between about 29.5 and about 50.5 weight percent and theweight percent of titanium is between about 29.5 and about 50.5 weightpercent, based upon the total weight percent of the alloy.

In some embodiments of the ocular implant, the body extends through anarcuate range between about 60 degrees and about 180 degrees. Atherapeutic agent may be deposited on the implant body in someembodiments. The therapeutic agent may be an anti-glaucoma drug, such asa prostaglandin analog (e.g., latanprost).

Another aspect of the invention provides a method of treating a humaneye, including the steps of: inserting an implant into Schlemm's canalof a human eye, the implant having a first flexibility when bent along afirst plane and a second flexibility different from the firstflexibility when bent along a second plane that intersects the firstplane and is not coincident with the first plane; and supporting tissueforming Schlemm's canal with the implant.

In some embodiments, the implant has an elongate slot, the methodfurther including the step of orienting the elongate slot radiallyoutward within Schlemm's canal. In some embodiments, the orienting stepis performed at least in part by permitting the implant to self-orientwith the canal. Some embodiments also add the step of providing fluidcommunication between an anterior chamber and the canal through theimplant.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a stylized perspective view depicting a portion of a human eyeand a portion of an ocular implant disposed in Schlemm's canal.

FIG. 2 is an enlarged perspective view showing a portion of the implantof FIG. 1.

FIG. 3 is a perspective view showing a volume defined by the body of theocular implant of FIGS. 1 and 2.

FIG. 4 is a perspective view showing a first plane intersecting the bodyof an ocular implant.

FIG. 5 is a perspective view showing a bending moment being applied toan ocular implant.

FIG. 6 is a plan view of the implant shown in FIG. 5 but in the absenceof any bending moment.

FIG. 7A is a lateral cross-sectional view of the ocular implant of FIG.6 taken along section line A-A of FIG. 6.

FIG. 7B is a lateral cross-sectional view of the ocular implant of FIG.6 taken along section line B-B of FIG. 6.

FIG. 8 is an enlarged cross-sectional view of the ocular implant of FIG.6 taken along section line B-B of FIG. 6.

FIG. 9 is an enlarged cross-sectional view of the ocular implant of FIG.6 taken along section line A-A of FIG. 6.

FIG. 10 is a plan view showing an ocular implant according to anotherembodiment of the invention having a longitudinal radius of curvaturethat varies along its length.

FIG. 11 is a perspective view showing an ocular implant according to yetanother embodiment of the invention that has substantially no radius ofcurvature.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a stylized perspective view depicting a portion of a human eye20. Eye 20 can be conceptualized as a fluid filled ball having twochambers. Sclera 22 of eye 20 surrounds a posterior chamber 24 filledwith a viscous fluid known as vitreous humor. Cornea 26 of eye 20encloses an anterior chamber 30 that is filled with a fluid know asaqueous humor. The cornea 26 meets the sclera 22 at a limbus 28 of eye20. A lens 32 of eye 20 is located between anterior chamber 30 andposterior chamber 24. Lens 32 is held in place by a number of ciliaryzonules 34.

Whenever a person views an object, he or she is viewing that objectthrough the cornea, the aqueous humor, and the lens of the eye. In orderto be transparent, the cornea and the lens can include no blood vessels.Accordingly, no blood flows through the cornea and the lens to providenutrition to these tissues and to remove wastes from these tissues.Instead, these functions are performed by the aqueous humor. Acontinuous flow of aqueous humor through the eye provides nutrition toportions of the eye (e.g., the cornea and the lens) that have no bloodvessels. This flow of aqueous humor also removes waste from thesetissues.

Aqueous humor is produced by an organ known as the ciliary body. Theciliary body includes epithelial cells that continuously secrete aqueoushumor. In a healthy eye, a stream of aqueous humor flows out of the eyeas new aqueous humor is secreted by the epithelial cells of the ciliarybody. This excess aqueous humor enters the blood stream and is carriedaway by venous blood leaving the eye.

In a healthy eye, aqueous humor flows out of the anterior chamber 30through the trabecular meshwork 36 and into Schlemm's canal 38, locatedat the outer edge of the iris 42. Aqueous humor exits Schlemm's canal 38by flowing through a number of outlets 40. After leaving Schlemm's canal38, aqueous humor is absorbed into the venous blood stream.

In FIG. 1, an ocular implant 100 is disposed in Schlemm's canal 38 ofeye 20. Ocular implant 100 has a body 102 including a plurality oftissue supporting frames 104 and a plurality of spines 106. Body 102also includes a first edge 120 and a second edge 122 that define a firstopening 124. First opening 124 is formed as a slot and fluidlycommunicates with an elongate channel 126 defined by an inner surface128 of body 102. With reference to FIG. 1, it will be appreciated thatfirst opening 124 is disposed on an outer side 130 of body 102.Accordingly, channel 126 opens in a radially outward direction 132 viafirst opening 124.

Ocular implant 100 may be inserted into Schlemm's canal of a human eyeto facilitate the flow of aqueous humor out of the anterior chamber.This flow may include axial flow along Schlemm's canal, flow from theanterior chamber into Schlemm's canal, and flow leaving Schlemm's canalvia outlets communicating with Schlemm's canal. When in place within theeye, ocular implant 100 will support trabecular mesh tissue andSchlemm's canal tissue and will provide for improved communicationbetween the anterior chamber and Schlemm's canal (via the trabecularmeshwork) and between pockets or compartments along Schlemm's canal. Asshown in FIG. 1, the implant is preferably oriented so that the firstopening 124 is disposed radially outwardly within Schlemm's canal.

FIG. 2 is an enlarged perspective view showing a portion of ocularimplant 100 shown in the previous figure. Ocular implant 100 has a body102 that extends along a generally curved longitudinal axis 134. Body102 has a plurality of tissue supporting frames 104 and a plurality ofspines 106. As shown in FIG. 2, these spines 106 and frames 104 arearranged in a repeating AB pattern in which each A is a tissuesupporting frame and each B is a spine. In the embodiment of FIG. 2, onespine extends between each adjacent pair of frames 104

The frames 104 of body 102 include a first frame 136 of ocular implant100 that is disposed between a first spine 140 and a second spine 142.In the embodiment of FIG. 2, first frame 136 is formed as a first strut144 that extends between first spine 140 and second spine 142. Firstframe 136 also includes a second strut 146 extending between first spine140 and second spine 142. In the exemplary embodiment of FIG. 2, eachstrut undulates in a circumferential direction as it extendslongitudinally between first spine 140 and second spine 142.

In the embodiment of FIG. 2, body 102 has a longitudinal radius 150 anda lateral radius 148. Body 102 of ocular implant 100 includes a firstedge 120 and a second edge 122 that define a first opening 124. Firstopening 124 fluidly communicates with an elongate channel 126 defined byan inner surface 128 of body 102. A second opening 138 is defined by asecond edge 122A of a first strut 144 and a second edge 122B of a secondstrut 146. First opening 124, second opening 138 and additional openingsdefined by ocular implant 100 allow aqueous humor to flow laterallyacross and/or laterally through ocular implant 100. The outer surfacesof body 102 define a volume 152.

FIG. 3 is an additional perspective view showing volume 152 defined bythe body of the ocular implant shown in the previous figure. Withreference to FIG. 3, it will be appreciated that volume 152 extendsalong a generally curved longitudinal axis 134. Volume 152 has alongitudinal radius 150, a lateral radius 148, and a generally circularlateral cross section 153.

FIG. 4 is a perspective view showing a first plane 154 and a secondplane 155 that both intersect ocular implant 100. In FIG. 4, first plane154 is delineated with hatch marks. With reference to FIG. 4, it will beappreciated that spines 106 of body 102 are generally aligned with oneanother and that first plane 154 intersects all spines 106 shown in FIG.4. In the embodiment of FIG. 4, body 102 of ocular implant 100 isgenerally symmetric about first plane 154.

In the embodiment of FIG. 4, the flexibility of body 102 is at a maximumwhen body 102 is bending along first plane 154, and body 102 has lessflexibility when bending along a plane other than first plane 154 (e.g.,a plane that intersects first plane 154). For example, in the embodimentshown in FIG. 4, body 102 has a second flexibility when bending alongsecond plane 155 that is less than the first flexibility that body 102has when bending along first plane 154.

Stated another way, in the embodiment of FIG. 4, the bending modulus ofbody 102 is at a minimum when body 102 is bent along first plane 154.Body 102 has a first bending modulus when bent along first plane 154 anda greater bending modulus when bent along a plane other than first plane154 (e.g., a plane that intersects first plane 154). For example, in theembodiment shown in FIG. 4, body 102 has a second bending modulus whenbent along second plane 155 that is greater than the first bendingmodulus that body 102 has when bent along first plane 154.

FIG. 5 is an enlarged perspective view showing a portion of ocularimplant 100 shown in the previous figure. In the exemplary embodiment ofFIG. 5, a bending moment M is being applied to body 102 of ocularimplant 100. Bending moment M acts about a first axis 156 that isgenerally orthogonal to first plane 154. A second axis 158 and a thirdaxis 160 are also shown in FIG. 5. Second axis 158 is generallyperpendicular to first axis 156. Third axis 160 is skewed relative tofirst axis 156.

An inner surface 128 of body 102 defines a channel 126. Body 102 ofocular implant 100 includes a first edge 120 and a second edge 123 thatdefine a first opening 124. Channel 126 of ocular implant 100 fluidlycommunicates with first opening 124. A second opening 138 is defined bya second edge 122A of a first strut 144 and a second edge 122B of asecond strut 146. First opening 124, second opening 138 and additionalopenings defined by ocular implant 100 allow aqueous humor to flowlaterally across and/or laterally through ocular implant 100.

As shown in FIG. 5, ocular implant 100 has a first spine 140 and asecond spine 142. First strut 144 and a second strut 146 form a firstframe 136 of ocular implant 100 that extends between first spine 140 andsecond spine 142. In the exemplary embodiment of FIG. 5, each strutundulates in a circumferential direction as it extends longitudinallybetween first spine 140 and second spine 142.

In the embodiment of FIG. 5, the flexibility of body 102 is at a maximumwhen body 102 is bent by a moment acting about first axis 156, and body102 has less flexibility when bent by a moment acting about an axisother than first axis 156 (e.g., second axis 158 and third axis 160).Stated another way, the bending modulus of body 102 is at a minimum whenbody 102 is bent by a moment acting about first axis 156, and body 102has a greater bending modulus when bent by a moment acting about an axisother than first axis 156 (e.g., second axis 158 and third axis 160).

FIG. 6 is a plan view showing ocular implant 100 shown in the previousfigure. In the embodiment of FIG. 6, no external forces are acting onbody 102 of ocular implant 100, and body 102 is free to assume thegenerally curved resting shape depicted in FIG. 6. Body 102 defines afirst opening 124 that is disposed on an outer side 130 of body 102. Achannel 126 is defined by the inner surface of body 102 and opens in aradially outward direction 132 via first opening 124.

Section lines A-A and B-B are visible in FIG. 6. Section line A-Aintersects a first frame 136 of ocular implant 100. Section line B-Bintersects a first spine 140 of ocular implant 100.

FIG. 7A is a lateral cross-sectional view of ocular implant 100 takenalong section line A-A shown in the previous figure. Section line A-Aintersects a first strut 144 and a second strut 146 of first frame 136at the point where the circumferential undulation of these struts is atits maximum. Body 102 of ocular implant 100 has a longitudinal radius150 and a lateral radius 148. An inner surface 128 of body 102 defines achannel 126. A first opening 124 fluidly communicates with channel 126.

In FIG. 7A, first opening 124 in body 102 can be seen extending betweenfirst edge 120A of first strut 144 and a first edge 120B of second strut146. With reference to FIG. 7A, it will be appreciated that second strut146 has a shape that is a mirror image of the shape of first strut 144.

FIG. 7B is a lateral cross-sectional view of ocular implant 100 takenalong section line B-B shown in the previous figure. Section line B-Bintersects first spine 140 of ocular implant 100. Body 102 has alongitudinal radius 150 and a lateral radius 148. In the embodiment ofFIG. 7B, the center 159 of lateral radius 148 and the center 163 oflongitudinal radius 150 are disposed on opposite sides of first spine140. The center 159 of lateral radius 148 is disposed on a first side offirst spine 140. The center 163 of longitudinal radius 150 is disposedon a second side of second spine 142.

FIG. 8 is an enlarged cross-sectional view of ocular implant 100 takenalong section line B-B of FIG. 6. First spine 140 includes a first majorside 160, a second major side 162, a first minor side 164, and secondminor side 166. With reference to FIG. 8, it will be appreciated thatfirst major side 160 comprises a concave surface 168. Second major side162 is opposite first major side 160. In the embodiment of FIG. 8,second major side 162 comprises a convex surface 170.

The geometry of the spine provides the ocular implant with flexibilitycharacteristics that may aid in advancing the ocular implant intoSchlemm's canal. In the embodiment of FIG. 8, first spine 140 has athickness T1 extending between first major side 160 and second majorside 162. Also in the embodiment of FIG. 8, first spine 140 has a widthW1 extending between first minor side 164 and second minor side 166.

In some useful embodiments, the spine of an ocular implant in accordancewith this detailed description has an aspect ratio of width W1 tothickness T1 greater than about 2. In some particularly usefulembodiments, the spine of an ocular implant in accordance with thisdetailed description has an aspect ratio of width W1 to thickness T1greater than about 4. In one useful embodiment, the ocular implant has aspine with an aspect ratio of width W1 to thickness T1 of about 5.2.

A first axis 156, a second axis 158 and a third axis 160 are shown inFIG. 8. Second axis 158 is generally perpendicular to first axis 156.Third axis 160 is skewed relative to first axis 156.

In the embodiment of FIG. 8, the flexibility of first spine 140 is at amaximum when first spine 140 is bent by a moment acting about first axis156. First spine 140 has a first flexibility when bent by a momentacting about first axis 156 and less flexibility when bent by a momentacting about an axis other than first axis 156 (e.g., second axis 158and third axis 160). For example, first spine 140 has a secondflexibility when bent by a moment acting about second axis 158 shown inFIG. 8. This second flexibility is less than the first flexibility thatfirst spine 140 has when bent by a moment acting about first axis 156.

In the embodiment of FIG. 8, the bending modulus of first spine 140 isat a minimum when first spine 140 is bent by a moment acting about firstaxis 156. First spine 140 has a first bending modulus when bent by amoment acting about first axis 156 and a greater bending modulus whenbent by a moment acting about an axis other than first axis 156 (e.g.,second axis 158 and third axis 160). For example, first spine 140 has asecond bending modulus when bent by a moment acting about second axis158 shown in FIG. 8. This second bending modulus is greater than thefirst bending modulus that first spine 140 has when bent by a momentacting about first axis 156.

FIG. 9 is an enlarged cross-sectional view of ocular implant 100 takenalong section line A-A of FIG. 6. Section line A-A intersects firststrut 144 and second strut 146 at the point where the circumferentialundulation of these struts is at its maximum.

Each strut shown in FIG. 9 includes a first major side 160, a secondmajor side 162, a first minor side 164, and second minor side 166. Withreference to FIG. 9, it will be appreciated that each first major side160 comprises a concave surface 168 and each second major side 162comprises a convex surface 170.

In the embodiment of FIG. 9, each strut has a thickness T2 extendingbetween first major side 160 and second major side 162. Also in theembodiment of FIG. 9, each strut has a width W2 extending between firstminor side 164 and second minor side 166. In some useful embodiments, anocular implant in accordance with this detailed description includesspines having a width W1 that is greater than the width W2 of the strutsof the ocular implant.

In some useful embodiments, the struts of an ocular implant inaccordance with this detailed description have an aspect ratio of widthW2 to thickness T2 greater than about 2. In some particularly usefulembodiments, the struts of an ocular implant in accordance with thisdetailed description have an aspect ratio of width W2 to thickness T2greater than about 4. One exemplary ocular implant has struts with anaspect ratio of width W2 to thickness T2 of about 4.4.

Body 102 of ocular implant 100 has a longitudinal radius 150 and alateral radius 148. In some useful embodiments, an ocular implant inaccordance with this detailed description is sufficiently flexible toassume a shape matching the longitudinal curvature of Schlemm's canalwhen the ocular implant advanced into the eye. Also in some usefulembodiments, a length of the ocular implant is selected so that theimplant will extend across a pre-selected angular span when the implantis positioned in Schlemm's canal. Examples of pre-selected angular spansthat may be suitable in some applications include 60°, 90°, 150° and180°. The diameter of an ocular implant in accordance with this detaileddescription may be selected so that the ocular implant is dimensioned tolie within and support Schlemm's canal. In some useful embodiments, thediameter of the ocular implant ranges between about 0.005 inches andabout 0.04 inches. In some particularly useful embodiments, the diameterof the ocular implant ranges between about 0.005 inches and about 0.02inches.

It is to be appreciated that an ocular implant in accordance with thepresent detailed description may be straight or curved. If the ocularimplant is curved, it may have a substantially uniform longitudinalradius throughout its length, or the longitudinal radius of the ocularimplant may vary along its length. FIG. 6 shows one example of an ocularimplant having a substantially uniform radius of curvature. FIG. 10shows one example of an ocular implant having a longitudinal radius ofcurvature that varies along the length of the ocular implant. An exampleof a substantially straight ocular implant is shown in FIG. 11.

FIG. 10 is a plan view showing an ocular implant 200 having a radius ofcurvature that varies along its length. In the embodiment of FIG. 10,ocular implant 200 has an at rest shape that is generally curved. Thisat rest shape can be established, for example, using a heat-settingprocess. The ocular implant shape shown in FIG. 10 includes a distalradius RA, a proximal radius RC, and an intermediate radius RB. In theembodiment of FIG. 10, distal radius RA is larger than both intermediateradius RB and proximal radius RC. Also in the embodiment of FIG. 10,intermediate radius RB is larger than proximal radius RC and smallerthan distal radius RA. In one useful embodiment, distal radius RA isabout 0.320 inches, intermediate radius RB is about 0.225 inches andproximal radius RC is about 0.205 inches.

In the embodiment of FIG. 10, a distal portion of the ocular implantfollows an arc extending across an angle AA. A proximal portion of theocular implant follows an arc extending across an angle AC. Anintermediate portion of the ocular implant is disposed between theproximal portion and the distal portion. The intermediate portionextends across an angle AB. In one useful embodiment, angle AA is about55 degrees, angle AB is about 79 degrees and angle AC is about 60degrees.

Ocular implant 200 may be used in conjunction with a method of treatingthe eye of a human patient for a disease and/or disorder (e.g.,glaucoma). Some such methods may include the step of inserting a coremember into a lumen defined by ocular implant 200. The core member maycomprise, for example, a wire or tube. The distal end of the ocularimplant may be inserted into Schlemm's canal. The ocular implant and thecore member may then be advanced into Schlemm's canal until the ocularimplant has reached a desired position. In some embodiments, an inletportion of the implant may be disposed in the anterior chamber of eyewhile the remainder of the implant extends through the trabecular meshinto Schlemm's canal. The core member may then be withdrawn from theocular implant, leaving the implant in place to support tissue formingSchlemm's canal. Further details of ocular implant delivery systems maybe found in U.S. application Ser. No. 11/943,289, filed Nov. 20, 2007,now U.S. Pat. No. 8,512,404, the disclosure of which is incorporatedherein by reference.

The flexibility and bending modulus features of the ocular implant ofthis invention help ensure proper orientation of the implant withinSchlemm's canal. FIG. 1 shows the desired orientation of opening 124when the implant 100 is disposed in Schlemm's canal. As shown, opening124 faces radially outward. The implant 100 is therefore designed sothat it is maximally flexible when bent along a plane defined by thelongitudinal axis of implant 100 as shown in FIG. 1, and less flexiblewhen bent in other planes, thereby enabling the curved shape ofSchlemm's canal to help place the implant in this orientationautomatically if the implant is initially placed in Schlemm's canal in adifferent orientation.

FIG. 11 is a perspective view showing an ocular implant 300 inaccordance with an additional embodiment in accordance with the presentdetailed description. With reference to FIG. 11, it will be appreciatedthat ocular implant 300 has a resting (i.e., unstressed) shape that isgenerally straight. Ocular implant 300 extends along a longitudinal axis334 that is generally straight. In some useful embodiments, ocularimplant 300 is sufficiently flexible to assume a curved shape whenadvanced into Schlemm's canal of an eye.

Ocular implant 300 comprises a body 302. With reference to FIG. 11, itwill be appreciated that body 302 comprises a plurality of tissuesupporting frames 304 and a plurality of spines 306. As shown in FIG.11, these spines 306 and frames 304 are arranged in an alternatingpattern in which one spine extends between each adjacent pair of frames304. The frames 304 of body 302 include a first frame 336 of ocularimplant 300 is disposed between a first spine 340 and a second spine342. In the embodiment of FIG. 11, first frame 336 comprises a firststrut 344 that extends between first spine 340 and second spine 342. Asecond strut 346 of first frame also extends between first spine 340 andsecond spine 342. Each strut undulates in a circumferential direction asit extends longitudinally between first spine 340 and second spine 342.

An inner surface 328 of body 302 defines a channel 326. Body 302 ofocular implant 300 includes a first edge 320 and a second edge 322 thatdefine a first opening 324. Channel 326 of ocular implant 300 fluidlycommunicates with first opening 324. First strut 344 of first frame 336comprises a first edge 325A. Second strut 346 has a first edge 325B. InFIG. 11, first opening 324 in body 302 can be seen extending betweenfirst edge 325A of first strut 344 and a first edge 325B of second strut346.

A first axis 356, a second axis 358 and a third axis 360 are shown inFIG. 11. Second axis 358 is generally perpendicular to first axis 356.Third axis 360 is generally skewed relative to first axis 356. Theflexibility of body 302 is at a maximum when body 302 is bent by amoment acting about first axis 356, and body 302 has less flexibilitywhen bent by a moment acting about an axis other than first axis 356(e.g., second axis 358 and third axis 360). Stated another way, in theembodiment of FIG. 11, the bending modulus of body 302 is at a minimumwhen body 302 is bent by a moment acting about first axis 356, and body302 has a greater bending modulus when bent by a moment acting about anaxis other than first axis 356 (e.g., second axis 358 and third axis360).

Many of the figures illustrating embodiments of the invention show onlyportions of the ocular implant. It should be understood that manyembodiments of the invention include an inlet portion (such as inlet 101in FIG. 6 and inlet 201 in FIG. 10) that can be placed within theanterior chamber to provide communication of aqueous humor from theanterior chamber through the trabecular mesh into Schlemm's canal viathe ocular implant. Further details of the inlet feature may be found inparent case U.S. application Ser. No. 11/860,318.

Various fabrication techniques may be used to fabricate the ocularimplant. For example, the ocular implant can be fabricated by providinga generally flat sheet of material, cutting the sheet of material, andforming the material into a desired shape. By way of a second example,the ocular implant may be fabricated by providing a tube and lasercutting openings in the tube to form the ocular implant.

The ocular implant of this invention can be fabricated from variousbiocompatible materials possessing the necessary structural andmechanical attributes. Both metallic and non-metallic materials may besuitable. Examples of metallic materials include stainless steel,tantalum, gold, titanium, and nickel-titanium alloys known in the art asNitinol. Nitinol is commercially available from Memry Technologies(Brookfield, Conn.), TiNi Alloy Company (San Leandro, Calif.), and ShapeMemory Applications (Sunnyvale, Calif.).

The ocular implant may include one or more therapeutic agents. One ormore therapeutic agents may, for example, be incorporated into apolymeric coating that is deposited onto the outer surfaces of thestruts and spines of the ocular implant. The therapeutic agent maycomprise, for example, an anti-glaucoma drug. Examples of anti-glaucomadrugs include prostaglandin analogs. Examples of prostaglandin analogsinclude latanprost.

While exemplary embodiments of the present invention have been shown anddescribed, modifications may be made, and it is therefore intended inthe appended claims to cover all such changes and modifications whichfall within the true spirit and scope of the invention.

What is claimed is:
 1. An ocular implant adapted to reside at leastpartially in a portion of Schlemm's canal of a human eye, the implantcomprising: a body configured to extend within the Schlemm's canal, thebody having a curved volume, a large radius side and a short radiusside, wherein a radius of the short radius side is less than a radius ofthe large radius side, the body having a circumferential extent withinthe curved volume that varies along the length of the body betweensections having a lesser circumferential extent and sections having agreater circumferential extent, one of the sections of lessercircumferential extent being disposed at a distal end of the body, thebody defining a channel extending longitudinally through the body to andthrough the distal end of the body, the channel having an open sidedisposed on the large radius side at one of the sections of lessercircumferential extent and an adjacent section of greatercircumferential extent and a plurality of openings along the length ofthe body on the short radius side, the openings being in fluidcommunication with the channel; an inlet portion configured to bedisposed in an anterior chamber of the eye when the body is in theSchlemm's canal, the inlet portion disposed on a proximal end of thebody in fluid communication with the channel, the inlet portion definingone or more openings adapted to be in fluid communication with theanterior chamber of the eye when the body is disposed in the Schlemm'scanal; and a distally facing sloped surface at the distal end of thebody formed by edges of one of the sections of lesser circumferentialextent at the distal end of the body and edges of a section of greatercircumferential extent proximal to the one section of lessercircumferential extent at the distal end of the body.
 2. The ocularimplant of claim 1 wherein each section of greater circumferentialextent comprises a respective pair of struts, the sections of greatercircumferential extent being separated from each other by the sectionsof lesser circumferential extent comprising spine sections, the strutsand spine sections defining the channel.
 3. The ocular implant of claim2 wherein a respective opening of the plurality of openings is disposedbetween its respective pair of struts.
 4. The ocular implant of claim 1wherein the plurality of openings are disposed opposite the open side ofthe channel.
 5. The ocular implant of claim 1 wherein the plurality ofopenings are disposed 140°-150° from the open side of the channel. 6.The ocular implant of claim 1 wherein the body is adapted to extendlongitudinally from a proximal end to the distal end at least about 60°around a circle formed by the Schlemm's canal.
 7. The ocular implant ofclaim 1 wherein the ocular implant is configured to provide a materialcoverage of the Schlemm's canal of less than 50% over 90% of the ocularimplant's length.
 8. The ocular implant of claim 1 wherein the ocularimplant has a resting shape extending longitudinally in a curve from aproximal end to the distal end.
 9. The ocular implant of claim 8 whereinthe resting shape forms an arc of a circle, the inlet portion lyingalong the arc.
 10. The ocular implant of claim 1 wherein the inletportion defines an open channel along at least a portion of its length,the open channel configured to be in fluid communication with theanterior chamber of the eye.